A Leica deformation monitoring system enabled Swiss authorities to evacuate an industrial zone before 300,000m3 of rock fell 1,000m from the Valegion mountain onto the valley floor near the village of Preonzo in Ticino canton. The authorities were also able to close the A2 highway ahead of the rockfall.
The region has suffered from periodic rockfalls with the largest occurring 10 years ago. Monitoring used to be carried out visually, but the Leica system was installed two years ago to automate the work.
Cantonal geologist Giorgio Valenti said the system showed that the movements ahead of the most recent rockfall increased to several millimetres per hour, making the evacuation necessary.
The system is based on a Leica TM30 monitoring sensor. It was installed on a stable pillar below the slide area and connected to the Leica GeoMoS monitoring system. The sensor monitors 15 observation points inside and outside the danger zone hourly and the results are automatically sent by SMS to experts.
Leica said the rockfall did not damage the road or the buildings in the industrial area.
Although the system can monitor the movement of the rock mass in 3D, it is impossible to predict the trajectory of the rock fall itself.